1. Field of the Invention
The present invention relates to an improved merchandise or shopping bag with an integral handle and reclosable feature. Particularly, the present invention relates to a bag with integral handles which includes a closure mechanism with male and female closure elements that is adapted for high speed and cost effective manufacturing.
2. Description of the Related Art
Thermoplastic films are used in a variety of applications. For example, thermoplastic films are used in sheet form for applications such as drop cloths, vapor barriers, and protective covers. Thermoplastic films can also be converted into plastic bags, which may be used in a myriad of applications. The present invention is particularly useful for bags constructed from thermoplastic film.
Polymeric bags are ubiquitous in modern society and are available in countless combinations of varying capacities, thicknesses, dimensions, and colors. The bags are available for numerous applications including typical consumer applications such as long-term storage, food storage, shopping, and trash collection. Like many other consumer products, increased demand and new technology have driven innovations in polymeric bags improving the utility and performance of such bags. The present invention is an innovation of particular relevance to food storage bags.
Polymeric bags are manufactured from polymeric film produced using one of several manufacturing techniques well-known in the art. The two most common methods for manufacture of polymeric films are blown-film extrusion and cast-film extrusion. In blown-film extrusion, the resulting film is tubular while cast-film extrusion produces a generally planar film. The present invention is generally applicable to bags manufactured from a blown-film extrusion process resulting in tubular film stock.
In blown film extrusion, polymeric resin is fed into an extruder where an extrusion screw pushes the resin through the extruder. The extrusion screw compresses the resin, heating the resin into a molten state under high pressure. The molten, pressurized resin is fed through a blown film extrusion die having an annular opening. As the molten material is pushed into and through the extrusion die, a polymeric film tube emerges from the outlet of the extrusion die.
The polymeric film tube is blown or expanded to a larger diameter by providing a volume of air within the interior of the polymeric film tube. The combination of the volume of air and the polymeric film tube is commonly referred to as a bubble between the extrusion die and a set of nip rollers. As the polymeric film tube cools travelling upward toward the nip rollers, the polymeric film tube solidifies from a molten state to a solid state after it expands to its final diameter and thickness. Once the polymeric film tube is completely solidified, it passes through the set of nip rollers and is collapsed into a collapsed polymeric tube, also referred to as a collapsed bubble.
One common method of manufacturing polymeric bags involves segregating the collapsed polymeric tube into individual trash bags by forming seals which extend transversely across the entire width of the tube with each seal forming the bottom of a bag. Typically, a line of perforations is formed immediately adjacent and parallel to each seal to facilitate separation of the trash bags one from another. The opening of the perforations then forms the top of a bag and opposing edges of the collapsed polymeric tube then form the opposing sides of a bag.
It is known to provide wave-cut bags by a continuous multi-bag manufacturing process from a collapsed bubble or tube. The collapsed bubble may be slit through both a front and back of the bubble with a repeating waveform pattern. Repeating evenly spaced pairs of transverse heat seals may be placed on both halves of the slit bubble to define left and right side edges of each bag. In between each pair of heat seals a perforation or cut line may be placed so that the formed bags may be separated. The slit middle of the collapsed bubble forms the top of the bag and one of the two opposing edges of the collapsed bubble forms the bottom of the bag.
The lobe-shaped features, or lobes, of wave-cut bags can have holes punched out or otherwise provided in the middle of the lobe to provide a convenient handle for the user to carry the bag. Unfortunately, if only a single lobe is provided on each side of the bag it is difficult to close the bag and if the lobes are used to tie the bag then the lobes no longer function as handles since their length is taken up in a knot. Hence, it would be useful to provide a cost-effective means to close the bag while still maintaining use of the bag's handles. Providing a means to reclose the bag also allows the bag to be repurposed as a storage bag after being used as a merchandise or shopping bag.
U.S. Pat. No. 4,125,220 (the '220 patent), filed Dec. 2, 1977 and hereby incorporated by reference, discloses a wave-cut shopping bag with a sinusoid waveform defining a top handle of the shopping bag. A width of the bag is disclosed as equal to a single wavelength with a hole or handle opening centered vertically on the base line of the wavelength and centered horizontally at the peak of the waveform. The '220 patent, however, fails to disclose any convenient means to close the bag.
Reclosable plastic bags are well-known in the art and are available in a variety of different sizes and configurations. Most commonly, reclosable plastic bags have one or more pairs of opposing, interlocking closures near the top opening of the reclosable bag. The closure may generally be opened and closed many times and are typically designed to ensure that the contents of the reclosable plastic bag are securely contained within the bag when the opposing closures are mutually engaged.
The closures of reclosable bags can be opened and closed in a number of different ways. For example, a slider or zipper device can be incorporated into the bag design to facilitate engagement and disengagement of the opposing closures. However, many reclosable bags have closures that are designed to be opened by physically pulling the closures apart and closed by pressing the closures together along the length of the closure. These bags may commonly be referred to as press to close reclosable bags.
U.S. Pat. No. 3,402,749 (the '749 patent), filed on Mar. 10, 1967 and hereby incorporated by reference, discloses a plastic film shopping bag with a reclosable zipper device and hand holes formed in integral flanges above the reclosable zipper device. However, the '749 patent relies upon straight cut upper flanges for handles which provides a difficult to grasp handle and fails to efficiently utilize material for forming the bag and its corresponding handles.
U.S. Pat. No. 4,165,832 (the '832 patent), filed on Jul. 10, 1978 and hereby incorporated by reference, discloses a side-gusseted shopping bag formed from a side-gusseted collapsed polymeric tube. Such bags are commonly referred to as “t-shirt” bags. The '832 patent discloses bags with integral handles but fails to disclose any means of closing the bag without the use of the bag's handles.
In consideration of the shortcomings of the above discussed prior art, it would be desirable to provide a merchandise or shopping bag having an integral handle and a reclosable opening. It would further be desirable to provide such a bag that takes advantage of high speed manufacturing processes and efficiently utilizes material. The present invention represents a novel solution to address these needs.